'\" te
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.TH DDI_INTR_GET_HILEVEL_PRI 9F "Apr 07, 2005"
.SH NAME
ddi_intr_get_hilevel_pri \- get minimum priority level for a high-level
interrupt
.SH SYNOPSIS
.nf
#include <sys/types.h>
#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>

\fBint\fR \fBddi_intr_get_hilevel_pri\fR(\fBvoid\fR);
.fi

.SH INTERFACE LEVEL
illumos DDI specific (illumos DDI).
.SH DESCRIPTION
Upon a successful return, the \fBddi_intr_get_hilevel_pri()\fR function returns
the minimum priority level for a high-level interrupt. The return priority
value can be used to compare to other priority values, such as those returned
from \fBddi_intr_get_pri\fR(9F), to determine if a given interrupt priority is
a high-level interrupt.
.sp
.LP
High-level interrupts must be handled without using system services that
manipulate thread or process states, because such interrupts are not blocked by
the scheduler.
.sp
.LP
In addition, high-level interrupt handlers must take care to do a minimum of
work because they cannot be preempted.
.sp
.LP
A typical high-level interrupt handler puts data into a circular buffer and
schedule a soft interrupt by calling \fBddi_intr_trigger_softint()\fR. The
circular buffer can be protected by using a mutex that is properly initialized
for the interrupt handler.
.sp
.LP
The \fBddi_intr_get_hilevel_pri()\fR function can be used before calling
\fBddi_intr_add_handler()\fR to help determine which type of interrupt handler
can be used. Most device drivers are designed with the knowledge that supported
devices always generate low level interrupts. On some machines, however,
interrupts are high-level above the scheduler level and on other machines they
are not. Devices such as those those using SBus interrupts or VME bus level 6
or 7 interrupts must use the \fBddi_intr_get_hilevel_pri()\fR function to test
the type of interrupt handler that can be used.
.SH RETURN VALUES
The \fBddi_intr_get_hilevel_pri()\fR function returns the priority value for a
high-level interrupt.
.SH CONTEXT
The \fBddi_intr_get_hilevel_pri()\fR function can be called from either user or
kernel non-interrupt context.
.SH ATTRIBUTES
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
.TE

.SH SEE ALSO
.BR attributes (7),
.BR ddi_intr_add_handler (9F),
.BR ddi_intr_alloc (9F),
.BR ddi_intr_enable (9F),
.BR ddi_intr_get_pri (9F),
.BR ddi_intr_trigger_softint (9F),
.BR mutex (9F)
.sp
.LP
\fIWriting Device Drivers\fR
